An 18-year-old female underwent a CT scan and subsequently an MRI scan of the lumbar spine at our department because of chronic low back stiffness and pain, extending in the sacro-iliac and coccygeal regions. The patient had been involved in a car accident one year before. There was no history of previous surgery. CT revealed a spontaneous hyperdensity of the dural sac (Fig. A, black asterisk) and the nerve root sheaths L4 to S1. MRI showed signal loss on both T1- and T2-weighted images of the dural sac (Fig. B-C, white asterisks), and nerve roots suggesting calcification. Furthermore, a plate-like hypo-intense structure was visible at the posterior leptomeninges of the lower thoracic spine (Fig. B-C, white arrows). Treatment with physiotherapy and paralumbar infiltrations was performed resulting in clinical improvement after 6 months.